We will attempt to establish that fascin is causal in the assembly of microvillar cores by microinjection of antifascin and muscle tropomyosin into sea urchin eggs. We will use the methods we have established for the isolation of the 95K protein from human platelets to search for a similar molecule or activity in egg cytoplasmic extracts. We will purify the egg 95K protein, or inhibitory activity, to homogeneity and begin to study its biochemistry. We will continue to study the affect of addition of muscle proteins on the actin-fascin interaction. We will attempt to reconstitute a contractile actin gel from actin, filamin and sea urchin myosin and will study the affects of added fascin and the 220,000 dalton protein on this system.